link(2) [osx man page]
LINK(2) BSD System Calls Manual LINK(2) NAME
link -- make a hard file link SYNOPSIS
#include <unistd.h> int link(const char *path1, const char *path2); DESCRIPTION
The link() function call atomically creates the specified directory entry (hard link) path2 with the attributes of the underlying object pointed at by path1. If the link is successful, the link count of the underlying object is incremented; path1 and path2 share equal access and rights to the underlying object. If path1 is removed, the file path2 is not deleted and the link count of the underlying object is decremented. In order for the system call to succeed, path1 must exist and both path1 and path2 must be in the same file system. As mandated by POSIX.1, path1 may not be a directory. link() will resolve and follow symbolic links contained within both path1 and path2. If the last component of path1 is a symbolic link, link() will point the hard link, path2, to the underlying object pointed to by path1, not to the symbolic link itself. RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error. ERRORS
Link() will fail and no link will be created if: [EACCES] A component of either path prefix denies search permission. [EACCES] The requested link requires writing in a directory with a mode that denies write permission. [EACCES] The current process cannot access the existing file. [EDQUOT] The directory in which the entry for the new link is being placed cannot be extended because the user's quota of disk blocks on the file system containing the directory has been exhausted. [EEXIST] The link named by path2 already exists. [EFAULT] One of the pathnames specified is outside the process's allocated address space. [EIO] An I/O error occurs while reading from or writing to the file system to make the directory entry. [ELOOP] Too many symbolic links are encountered in translating one of the pathnames. This is taken to be indicative of a looping symbolic link. [EMLINK] The file already has {LINK_MAX} links. [ENAMETOOLONG] A component of a pathname exceeds {NAME_MAX} characters, or an entire path name exceeded {PATH_MAX} characters. [ENOENT] A component of either path prefix does not exist, or is a dangling symbolic link. [ENOENT] The file named by path1 does not exist, or is a dangling symbolic link. [ENOSPC] The directory in which the entry for the new link is being placed cannot be extended because there is no space left on the file system containing the directory. [ENOTDIR] A component of either path prefix is not a directory. [EPERM] The file named by path1 is a directory. [EROFS] The requested link requires writing in a directory on a read-only file system. [EXDEV] The link named by path2 and the file named by path1 are on different file systems. SEE ALSO
symlink(2), unlink(2) STANDARDS
The link() function is expected to conform to IEEE Std 1003.1-1988 (``POSIX.1''). 4th Berkeley Distribution October 29, 2008 4th Berkeley Distribution
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SYMLINK(2) BSD System Calls Manual SYMLINK(2) NAME
symlink, symlinkat -- make symbolic link to a file SYNOPSIS
#include <unistd.h> int symlink(const char *path1, const char *path2); int symlinkat(const char *name1, int fd, const char *name2); DESCRIPTION
A symbolic link path2 is created to path1 (path2 is the name of the file created, path1 is the string used in creating the symbolic link). Either name may be an arbitrary path name; the files need not be on the same file system. The symlinkat() system call is equivalent to symlink() except in the case where name2 specifies a relative path. In this case the symbolic link is created relative to the directory associated with the file descriptor fd instead of the current working directory. If symlinkat() is passed the special value AT_FDCWD in the fd parameter, the current working directory is used and the behavior is identical to a call to symlink(). RETURN VALUES
Upon successful completion, a zero value is returned. If an error occurs, the error code is stored in errno and a -1 value is returned. ERRORS
The symbolic link succeeds unless: [EACCES] Write permission is denied in the directory where the symbolic link is being created. [EACCES] A component of the path2 path prefix denies search permission. [EDQUOT] The directory in which the entry for the new symbolic link is being placed cannot be extended because the user's quota of disk blocks on the file system containing the directory has been exhausted. [EDQUOT] The new symbolic link cannot be created because the user's quota of disk blocks on the file system that will contain the symbolic link has been exhausted. [EDQUOT] The user's quota of inodes on the file system on which the symbolic link is being created has been exhausted. [EEXIST] Path2 already exists. [EFAULT] Path1 or path2 points outside the process's allocated address space. [EIO] An I/O error occurs while making the directory entry or allocating the inode. [EIO] An I/O error occurs while making the directory entry for path2, or allocating the inode for path2, or writing out the link contents of path2. [ELOOP] Too many symbolic links are encountered in translating the pathname. This is taken to be indicative of a looping symbolic link. [ENAMETOOLONG] A component of a pathname exceeds {NAME_MAX} characters, or an entire path name exceeds {PATH_MAX} characters. [ENOENT] A component of path2 does not name an existing file or path2 is an empty string. [ENOSPC] The directory in which the entry for the new symbolic link is being placed cannot be extended because there is no space left on the file system containing the directory. [ENOSPC] The new symbolic link cannot be created because there there is no space left on the file system that will contain the sym- bolic link. [ENOSPC] There are no free inodes on the file system on which the symbolic link is being created. [ENOTDIR] A component of the path2 prefix is not a directory. [EROFS] The file path2 would reside on a read-only file system. In addition to the errors returned by the symlink(), the symlinkat() may fail if: [EBADF] The name2 argument does not specify an absolute path and the fd argument is neither AT_FDCWD nor a valid file descriptor open for searching. [ENOTDIR] The name2 argument is not an absolute path and fd is neither AT_FDCWD nor a file descriptor associated with a directory. SEE ALSO
ln(1), link(2), unlink(2), symlink(7) STANDARDS
The symlinkat() system call is expected to conform to POSIX.1-2008 . HISTORY
The symlink() function call appeared in 4.2BSD. The symlinkat() system call appeared in OS X 10.10 4.2 Berkeley Distribution June 4, 1993 4.2 Berkeley Distribution